London HEMS is two crew and I believe pilots need IR. They were advertising recently.
How about Premier (S76), or JCB (your neck of the woods).
As for the NATS comment - not a bad idea. Appreciate your thread was 'how do I get flying again' but for info my friend is just about to qualify on Tower at an oop north airport (salary in the region of 30 to 40k) and has a radar course pencilled in (20k more!) so the money is there (not bad compared to some of the london based taxi driver salaries!)
I don't know how the medical would work but you normally have an assistant at busier places and there is normally at least 3 ATCOs working at once at this particular airport (they try rotate 1 tower, 1 radar, 1 break) so I guess there is a second crewman available should a medical problem manifest itself whilst you are at work.
Im not convinced its a good time to get into instructing at the moment as there is very little work around.