Hi Paul and welcome to the forum. I have no experience of pigeons as I just started last year but, I can tell you what I have found.......think carefully how many birds you will keep..I started with a 4x6' shed, progressed to a garden shed and now have just bought a 12'x6' shed and would still like more room. I have found it much cheaper to buy a good quality garden shed and convert it to a loft. Having said that, you might be lucky enough to find a secondhand loft - I think that there are some on the forum at the moment. Be careful where you get your birds from...there are a lot of feather merchants out there...I learned the hard way....the most expensive is not necessarily the best.
This forum is great for advice but, you can't beat hands on advice from a local fancier......when I think my birds are ill my 'pigeon man' comes straight round and checks them for me.
Read and ask - the only stupid question is the one you don't ask - believe me, I know, I've asked plenty. ;D
Good luck
Sue