Lola now 5 months old, is scared of everything, lead, collar, halti, loud noises, dogs of all sizes etc.

She has been to training where she came top of the class with 2 points off full marks. Recall spot on, heel work spot on etc (I think the lost two pints were for my shocking dress sense). This all changed on a walk. I was unwell and the OH took Lo out on the usual excursion, leaving me in bed with Boxer laying by my side whilst I slept. He got maybe half way (Lo off lead at the end at this point), she then bolted and ran...and ran..eventually finding her way out (very secure, partner ripped his jeans and half his dignity  yompping over the fence) down a very busy  road with him staying calm (more than I would of, dignity intact or not) but in hot pursuit. Then she crossed the road turned around sat then crossed again.  When the OH caught up she was sat by the front door. (this was not a route we normally take as cars park on the pavement forcing us to walk onto a very busy road). Lola has separate walks from the Boxer and some together. Just with me or the OH. This has unnerved us a little. This occured a few weeks before the fire works (this has not helped one bit)

Given the choice Lo would sit outside and just watch the world go by, kites flying, the leaves falling and a little bit of sunshine. In the park, she would watch the Boxer running, playing, sniffing. Interacting for a while, until she appeared to hear a bird, little wag of the tail she would sit and watch.  But she works out any game, sent games, hide and seek, her learning ability is nothing I have experienced before. But the lead....collar,  halti makes her hide behind her bed. She has pulled covers over herself so you can't see her. Any suggestions????? She is driven by food but this hasn't helped. Once out, she is fine...apart from bolting home

Cant offer and suggestions but I understand and am still working in the lead collar car with my pup. No rhyme no reason but I recognise the bolt to hide. Once out loves everthing and not really a scardy cat.
Food is her motivation but not in this situation, taking her out with the other dog helps once you have got her on the lead but getting her there is the difficult bit.
Good luck

Turn it into a game, and don't use the halti for a little while while you work on it (ideally not the lead either if she's scared of both so she may be stuck at home for a few days unless you can drive her somewhere she's safe off lead and keep the lead on you for emergencies).

Rather than just trying to get her used to it, approach it from a different angle.  I've read recently of someone having great success with a dog scared of his lead and harness by doing targetting with them rather than trying to make the putting-on experience better - by taking it completely out of context he's improved a lot.

Doesn't have to be anything fancy - just having the halti laid somewhere and when she goes near it, reward her (clicker works great for this, or a quick clicker word that means treats like 'yes!').  As she gets closer, reward her only for the closest sniffs, and then for touches with her nose.

You should find she'll start to target it by herself - touching it with her nose for a treat.  Do the same with the lead as well (separately at first, and then together) until she's really excited about them - then you can start working on putting them on her again.  Baby steps - nose-touches with you holding them to start with, then with her nose through the loop (and take it off straight away), then with it done up and taken off, so on and so forth until she's happy for you to put it on and walk a little bit, then take it outside - go back a step to start with (so start from her putting her nose in only and build up again) as it's a different environment and dogs aren't good at generalising training in different places.

As for the scared outside - get yourself a copy of Behavioural Adjustment Training by Grisha Stewart, or look it up on youtube - that'll help you teach her how to 'control' her environment and the scary things and should build her confidence no end.  Do NOT try to force her to socialise - if she's scared and you try to expose her to things too much she'll only get more scared.  If she reacts, walk her away - you're too close.  Everything needs to be started at a distance she's comfortable with and built up from there - with a scaredy dog I tend to start far away and shovel the dog full of food before they start tensing up, to get the good associations going.  Then I start to move closer carrying on the rewards - BAT however uses 'functional rewards' (i.e. distance from the scary thing as opposed to food) and so far seems to be fantastically effective and quicker, so I'm looking into that for my reactive dog at the moment.