I got offered a local school (but not too local - you do not want to be bumping into kids all the time, strict rules about out of school contact) and accepted. I was lucky in that they let me do 9-10.30 (ie during literacy/numeracy) whereas lots of schools only wanted after lunch which really breaks up the day.
I worked with year sixes - for some, the job was as much trying to provide a calm, positive experience and gently foster conversation/enjoyment of books as anything - they were way way behind but there were lots of barriers. In my last year especially the year head was great and really engaged with me about one troubled lad which meant i was better able to support him and could tweak the sessions to suit him/support the class teacher. If the school is not supportive/committed, do raise it early on with BS. You should not be fighting for decent space, the allocated time, chance to do what you are there for not what the school wants (other than very occasionally). And do try to find a way of knowing when school trips are on so you don't have wasted journeys. When dc were ill, the school would usually ask me to read with a good reader that I didn't know as a treat for them, which was great!
Having waved my own dc off, it was a tie - i felt bad going away in term time as the kids minded (especially those that claimed to hate reading 😀). That's one reason I've not gone back. I also became attached to the children and they to me, and it was hard when one made safeguarding disclosures. Beanstalk was going through a tricky time then too - but I did really like having the external support and training, and a chance to meet other people doing the same thing.
The school let us (they had about 5 BS readers, were really committed) each keep a box in a cupboard. I used to buy books at charity shops and also got a teacher's pass for the local library (20 books, no fines). And I would keep maybe a word game, a crossword book, a conker, a fiddly thing, things to talk about in there. The children liked choosing books and having a special box. If you work with older children like I did, and can gain their trust enough for them to let their guard down and engage with books they can actually read and enjoy instead of ones "for" their age - it is magic seeing their confidence grow. Roald Dahl's verses were great with this age too, as we'd do a line each and they could guess....I could go on but will stop there!