You need to look at your financial budget - properly (squeezing teabags isn't going to save you the amount you are looking at).
And then having fully itemised EVERYTHING you spend in a year you need to look at what you can cut back on.
Do you have Sky - that can be £40pm? That's nearly £500pa. A freeview+ box would cost you under £100, so that's £400 saved in the first year.
Look at all utilities and whether you can get them cheaper.
Look at your utility usage - tumble drier, heating down a notch etc.
Food bills - can you "go down" a level, move from finest to normal, from normal to value. There are things where you wouldn't notice any difference other than in your pocket.
Cars - do you run 2, could you live with 1?
Hobbies, sports, gyms etc
The coffee on the way to work, or the sandwich for lunch every day.
If you really want to do this you, and everyone else in the family, needs to be committed to seeing where the money goes, and to cutting back on it.
As a final point, I have a friend who is repaying approx £800 pm extra off the mortgage - but after that has very little spare cash. She as talked about how in 5/10 years they will be able to take the kids on nice family holidays, etc.
TBH this seems a bit mad to me - if they didn't repay that extra it would be £10k a year. They could repay say £5k, and have more to spend on life now - and still repay the mortgage early. Or not repay any, and still have the mortgage repaid by the end of it.
There are happy medium's - yes plan for the future, but not at the expense of the present.