Your Dc are not deprived OP, they have a wonderful Mum.
I have been in your situation and you just need to get creative with your activities. We have DC who now can;
Ride (helped out all day doing character building lead rein at the riding school for a free lessons at the end of the day).
Ski, we went to Scotland and learned there.
Camp and fish.
Know a hell of a lot about nature/birdwatching, identifying funghi and wildflowers/trees. All learned from being in the great outdoors.
Play instruments, thanks to our local brass band who taught them all to read music and loaned them instruments (all for £2 a week), a local youth orchestra also teaches/loans instruments for free. Our youngest also sings in a church choir, choral grade tuition free and they pay him!!.
Cadets, amazing organisation, army cadets seems to be much cheaper than air cadets for some weird reason. Uniform provided, 2 week all action summer holiday for £60 including kayaking, going for rides in helicoptors, coasteering etc. We avoided scouts and guides though, so expensive.
Compete at national level in their chosen sports, you just have to be careful re which ones! some that you might think are expensive are actually heavily subsidised. Join a club instead of paying for individual private lessons eg swimming, sailing, rowing.
Libraries were invaluable to us, not just to borrow books but also to find out what was on locally and cheaply.
We give experiences rather than gadgets for birthdays/Xmas and the older ones have avoided the pull of sitting in front of a screen all day. Youngest would spend every penny on computer games though so I think we ran out of steam with him!