Paris

I think you're going to have an issue. I travel a lot through Paris for work, and can tell you it is a very expensive place. Three (I assume) of you need to get there, and stay in a hotel for 3 nights. I would imagine that during school holidays that'll eat up most of your £500.

I now that's not what you want to hear, but even things like transfers in the UK before leaving and once home could eat into that.

If you're adamant that you have to go, pick the major airport closest to you with a budget airline. Go hand baggage only, and find something like an Ibis Styles hotel in Paris. I've not used Orly airport, but have used Charles De Gaulle many times. It's one the worst airports I've been to anywhere in the world.

Good luck - I hope you find something that suits.....

You might manage travel and accommodation but I think you struggle to cover much else. We're going on cheap Eurostar tickets over the last few days in July - £58 for me and a few pounds less for the kids but still at least £150 for all three of you. You might get a flight cheaper but with transfers I don't think you'll save much. I was struggling to find hotel rooms that were central for less than £100 per night - the exchange rate isn't in our favour. You might find something a bit further out but if you're after three beds you might have less choice or prefer two rooms. We opted for a Airbnb in the end but that isn't much cheaper. There are lots of hostels in Paris where you can get private rooms as well as dorms. Some very nice ones like this - www.lespiaules.com.

We went to Paris in April. 2 adults 2 kids. It was pricey
Flights to Beauvais €250
Car hire €60
hotel for one night €150, it was in Versailles and was lovely.
Open top bus tour €100
Food and spends probably another €300.
It was lovely though. We really enjoyed it.