Random days out in summer holidays - grateful for any recommendations!

[gardeningirl]

Can't afford a holiday abroad but have saved a little for a few days away or to visit attractions in UK this summer holidays...

We are in Hertfordshire but happy to stay local or travel country wide for a day or two away.
Kids are 8 and 11 - any suggestions? At the moment we have absolutely nothing planned for the whole summer so I'm feeling like a rubbish mum!
So far musing on a couple of nights at the seaside maybe camping or B@B, a trip to London, maybe a trip to Edinburgh???
Thanks in advance

Day trips:
Woburn Safari Park
Bekonscot Model Village and Railway. This is 35mins away from Go Ape Wendover Woods which now has Go Ape and Go Ape Junior.
Imperial War Museum Duxford in Cambridgeshire
Paradise Wildlife Park

Do you drive? There are a good couple of campsites in Birchington and then you have the Kent coast to discover. A day at Broadstairs beach, a visit to Dover castle, wingham wildlife park, quex Park, dreamland in Margate.