I have seen a van advertising gas installation work and think it was backed by Corgi registration at Mountbatten marina. Could be worth a try, I will be there this weekend if no one else comes up with the goods I will try and find a telephone number.
I used SSG at Millbrook last year, after the insurance people demanded I replace my aged Lytham mariner hob and grill.
SSG came out to Cargreen on a Saturday morning, supplied and plugged in a replacement, tested the installation thoroughly and issued a certificate then and there.
Pretty satisfactory all round, only a minor gripe in that I understood he was going to actually install the new hob and grill, rather than leave that bit to me, but it was hardly onerous.