Wow 18,50 sounds like a lot. I already thought that the 8 or how much it was for the Santa?s Grotto in Horniman was a lot, def not worth it. Went to Winter Wonderland after that and saw the Santa for free there and was much nicer.
When my baby was 2 months he also needed an allergy test asap and the referral from nhs took 2 months. I just called them to call me back if there are any cancellations and got an appointment within a week.
I agree with canela, I would try to travel as much as possible with just having one, as it gets so much more complicated with two and also more expensive.