
You can take your bitch out on lead only around the streets etc, but on no account anywhere that dogs are entitled to be running free.
Whether you do so will depend a lot on whether your area is free of roaming/latchkey dogs. With her size you do have the advantage of picking her up.
I always road walk my in season bitches, and if I spot someone else with a dog on lead I cross to the other side of the road so as not to distract/attract their dog. If the owner has the dog on rather a long lead or seems not to be paying attention, I may shout out that I have a bitch in season, as I don't want them dragged into the road :D
It is totally unacceptable, foolhardy and selfish to take a bitch in season to a public park or open ground where dogs are exercised off lead. The most biddable and placid dogs may be deaf to all commands or get into fights over a bitch in season. It is very unfair on the male dogs owners (an even bitches are distracted/interested by the smell of a bitch in season), as they are unaware of the situation until their dog is off over the horizon after the bitch.
To be on the safe side you shoudl keep your bitch away from all entire male dogs for 28 days from the start of the season. The average season lasts 21 days, but many bitches ahve been mated and had puppies after a mating on days 23 and later.
It is entirely up to you which vet you use.