Right, woah loads of questions and of course each primary care trust is different but where I am and how it happened for me was...
First time got ill was hospitalised, nice gastro doc came to see me on the ward and explained what was going on, he became my GI. He took care of deciding what meds I was to go on etc and the reported to my GP what these were so I could go and get repeat prescript
ions from her - I don't even have to see her just drop a repeat prescript
ion form in and pick it up again. When I am in remission I see my GI every 6 months for a check up but when I get a flare I phone the IBD nurse who will talk and advise me and also fit me in ASAP with my GI.
For any other illness or pain which isn't massively urgent I go to my GP, I also have something called Shared Care once every four weeks to keep an eye on my meds and my health, which is where I have a long appointment with the GP and have a check up - blood and urine tests, blood pressure, general chat about my health and gives me a chance to ask for advice if any in needed. I tend to deal with my GP the most, but do have an email relationship with my IBD nurse if I have any questions.
It is easier dealing with a GP I think, I find that if theres anything they don't know or are unsure about they just phone up the hospital and can usually get through to someone over there who has a vague idea and it gets resolved quite quickly. But you do really need a GI too, if you end up needing some of the hardcore meds such as infliximab it can only be prescribed by a GI and ideally you should be having check ups once or twice a year to keep an eye on things, there can be a wait for a GI so you may want to get a referral in now in case you have a long wait for an appointment. Once you've had that first appointment you should be able to see them as little or as often as you need to, but its worth getting in the loop now rather than wait until you really need one.