Thanks for the new thread Reastie 
I'm glad the bungee bouncer was helpful. A little more expensive, but even more fun are these pedal racers at £18.95 plus £3.95 delivery (free if you spend over £35)
Amazing fun, and take my weight easily I certainly don't play on them when the children are at school and I'm meant to be working
@VoldemortsNipple DS has the echo dot (saved up and bought it himself, bless him) and teenaged-DSS has the full-size echo. The big one is a proper speaker and LOUD. The echo is, in my opinion, perfect for a younger child's bedroom as it's still loud enough at top volume for them to have 'bedroom discos', but not so much that you can hear it though 3 closed doors on the other side of the house IYSWIM. They both use it with their spotify subscriptions.
@WhyamIBoredathome DD was 5.5 when we got our bungee bouncer and picked it up instantly. Not sure about 4 years old, but would guess it would be ok. It's so much easier than a pogo stick.
Thank you to whoever recommended Stikbot. I'm hoping it'll be included in the Argos 3 for 2, if it runs.
I've decided against the lego drone for DD (I think she'll get frustrated if she can't fly it properly), but will drop some hints in the hope that someone buys it for me!