The thing with the NHS is that they have a list of things to 'try' and injections are one of them. Fair enough in some ways, as an operation is more risky and costly and for some people the injections do the trick. They didn't for me sadly, but they are worth a go.
If injections are what they're going for, then make I'd say ask lots of questions in terms of why they think it might work and what type of injection they'll be giving you - I think from memory there are 3 different types. I went through all of them. Also I'd ask what happens if the injection doesn't work. ie how long they give it to work, and then how soon you get a follow up appointment/ what will happen next if it doesn't work, etc.
If for example they suggest that an operation might be the next thing, then ask them how long that referral takes and see if they'd let you meet the Consultant for potential surgery alongside having the injections?
I really did find it vital to feel in control of it all - you can drift for months in the system if you're not. Getting direct phone numbers to clinics, calling through for cancellations, earlier appointments, etc - all of that can save you months of back ache. Good luck with it all - yell if you think I might be able to help and I'll try to - I do so remember how gnawing that pain is. If I can come through it though, so can you. Oh and a large glass of wine most definitely helps.. 