You could be there for hours depending on their interest. There's more to it than the ground floor. The lower ground has a really interesying exhibition with household gadgets from down the years, the upper floors have hands on experiments and then there's all the stuffed animals models. You could spend all day there if you wanted. If you only have a few hours, maybe plan in advance what sections you want to visit.
Thanks, we ended up at Madame Tussaudes and surrounding area with Sylvia Young being one of her tourist attractions lol. I think she will be seeing a lot of London and she has already decided to move down at some point so will defo be doing the science museaum. We only had about 6 hours to kill yesterday. It had been a working break for DD and we were just picking her up to come back home. We have now decided to have a short fun stay, so will defo do the science museaum plus others. Would be easier if we lived closer. Think I will take a day out to do the science museaum so it's not rushed. Thanks again.