"and trying to think of this as a home rather than just an investment"
It very much is your home. Unless you are renting it out, a house is not an investment. Technically it's a liability. It doesn't give you a return and you have to pay to maintain it.
People in the UK seem to be conditioned to the whole "my house is my biggest asset" thing; it really isn't. It's a home, unless you are renting it out.
Large capital gains due to rises in the market are great, if they happen. But they don't always, and people are foolish to rely on them.
You presumably bought this house as you liked it and it's in your desired location etc etc.
Obviously you can only do what you can within your financial means, but yes, I think you need to separate the fact that you think you overpaid for it, from the fact that it is your home and you absolutely should do what you can to make it comfortable.
If you live in a house for 10, 15, 20 years, overpaying a bit for it really doesn't matter. And the rising interest rates you would have whatever house you were in.
Also think about the fact that you are no longer paying rent, which is dead money; that will offset how much you overpaid by somewhat.