Hi Lapcat, I was roughly the same as you. Married at 10st, went up to 14 stone for a few years, got down to 12.5st, stayed there for a few years. Made a huge effort to get down to 10st and then managed 9.5st but only for a short while. Put on a stone in the last few months alone so have joined here as I know I would have put on another stone and then another by summer if I didn't reign it in. I'm also in my 40s.
I don't do any formal exercise at all, no gym, swimming, running, nothing. I do walk a lot and I'm very busy, constantly moving around etc because of the kids.
I don't think you have to do formal exercise to lose weight. In a way I think it's easy to believe exercise equals weight loss but in my experience erecuse is for fitness and diet is for weightloss (and health). Both equally important but if it's weightloss you want to tackle first then diet is the main thing. You'd have to be a professional athlete or exercising hard every day to burn off lots of extra calories! 
Getting down from 14.5 st was mainly only drinking on social occasion and not at all the rest of the time. Also limited rubbish fir most days, treats occasionally or again on occasion. For a bog standard ordinary day (i.e. no social reason or special occasion) then it was bog standard food and drinks. That means breakfast lunch dinner with the odd snack, no cake, no wine, no takeaway etc. You can't lose weight if you are eating and drinking that stuff daily or every other day, at best you might maintain your weight but you won't lose anything.
It really requires a total shift in what you count as "usual food and drink consumption". Most of us are used to eating far too much and counting it as normal food. E.g. I was so used to eating half a packet of biscuits or equivalent daily plus crisis, snacks etc i was actually surprised if I only had a quarter of a packet of biscuits and didn't lose like 5lb the next day I really just could t see it. Also my portion sizes were massive.
Two books that really helped were the greedy girls cookbook and the hairy bikers one. The hairy bikers suggested only two spoons of rice with a chilli meal for example. I was like 
that's tiny, as I was used to the classic mountain of rice. But now I see it was far too much. I thought as it was "proper food" and not rubbish it didn't count how big the portion sizes were. Also I threw out all my usual favourite sugar treats and only bought boring snacks I wasn't particularly keen on.
Sorry for extra looooong post but I could really identify with you and I just wanted to share my experience with you. It is possible to rewrite your old habits but you have to get your head around it all first. I tried and failed so many times before and I didn't really understand why.
You can do it, anything is possible. Support like this thread makes a huge difference as you don't always want to share the ups and downs with friends or family and it's daily encouragement. Losing weight can be lonely and it's easy to get disheartened at slips but if you keep having more good days than bad then you will get there x