Thank you everyone for your comments and opinions, I am sorry if I appear rude by not answering every comment as they were posted. I am a busy working single mum to two teens. As I said its not my intention to be rude here.
Probably easier now to answer some of your questions and points here.
Several of you seem to object to "girl or boy mode" well our family were using these phrases long before Eddie Izzard ever did! My son spends time dressed and behaving like a boy and also time dressed and behaving as a girl hence the different modes, I can not see why that is a complicated concept or would offend anyone.
The last thing I want to do is give him a label or push him down any particular path.
I get tired of the constant nit picking over what I should label him or describe him as, oh your using the wrong name or label...... Least of my worries to be honest.
Maybe this is just crossdressing more than anything deeper. But still this is going to be a part of who he is for ever and I feel hat as he goes through life he will need support with this at certain stages and this is one of those milestones.
I did say that although I used "Trans" I am not sure and not convinced that it applies to him.
Yes I am bloody confused and uncertain of my actions in the past and now.
Yes he has friends and yes is able to meet with them, but I would not be happy if he was going out in girl mode on his own, I honestly don't think that he would at the moment.
He has always had a preference for girls clothes, and would spend the odd day or even a few hours in the evening dressed in something.
Over lockdown he was dressing a lot more, days on end. I even posted on here for advice as I was worried about him adjusting back to normal life.
He still spends a lot more time in girl mode than he ever did, and has been pushing boundaries when he has to be in boy mode, underwear choices etc.
The main reason to chose a town further away is really just to minimise the risk of meeting anyone we know, it would just be nice to enjoy the experience without having to explain or risk him feeling uncomfortable.
I have no worries at all about him "passing" there is absolutely no way that you would think he was anything other than just another teenage girl, he wouldn't want to stand out but just blend in with everyone else.
I don't think we need to worry about changing rooms for his trip out but if he needs a wee I have to agree with another poster that the Ladies would be the safest and best option.
Remember his sister and I will be with him all the time.
This isn't about a boy putting on a dress for a walk, he will be presenting as a girl, that's what he wants to experience, just to be out and about without a care.
As I said thank you all for your comments, but particularly the more encouraging ones, you are helping my confidence and in turn his.