my ipad software version needs updating

You clearly have an iPad 4th generation. As such, iOS 10.3.3 is the most current version for your iPad, which is now out of date and no longer supported. Your device is too old and under powered to run the newer iOS versions.

The simplest answer (though some other members, will chime in long answers here) is that if you need the newer iOS levels for the many apps which will no longer run on a 4th gen iPad, you need a newer iPad capable of running the newer versions.

If there are apps, which you want, yes, time to spend some money. Even the least expensive new iPad sold today by Apple, has the latest processing power and will be infinitely more powerful than your 4th gen iPad and run the latest iPadOS versions for several years going forward.