Many thanks, peeps, for your info and advice. I have no experience of unspeyed females at all, my old girl was speyed before I got her and my two young kittens, Sophie and Rosie, I know aren't speyed and I'm just waiting for them to reach the right age to get them done before I let them loose on the world. Tina's grounded in any event until her wound is completely healed and she has her second jab and is microcipped (3 weeks) I am hoping that by that time she will have shown clear signs of being in heat so I can go ahead with getting her speyed knowing she isn't being opened up for no reason. It's so much easier with the boys. I will discuss it in more depth with my vet in 3 weeks time. Provided she is physically fit enough for the op I would rather they went ahead than risk her getting pregnant. As Gill said, we will be sure she is speyed before she is rehomed. I want to send her off with the best possible chance - fully healthy, chipped, vaccinated and speyed.
Gill: I weighed her again this weeked but unfortunately she doesn't appear to have put on any weight although she is eating well. However, this was just measured with my scales so might not be too accurate.