Probably not...sorry!
Of course, the real answer is yes, of course you can find someone to look after your dts all day who will accept a low rate of pay in return for living in your home and scraping a bit of an income, because there's a global recession on, and there are girls (and boys) from all sorts of EU countries and beyond who are desperate for any chance to improve their lives.
However...you're not going to find someone with reasonable childcare experience at aupair rates. I'm not being 'judgey' but the idea of having an aupair is that they help you for a few hours a day, or for a few days a week, normally for up to 30 hours in total (including any cooking/cleaning etc), in return for board, lodging and about £100/week 'pocket money', and time to attend language school or just travel around and learn about a different culture.
We're on our 2nd aupair, and they have both been lovely girls, who I've been happy to entrust my 3 dcs to for a few hours a day, but definitely not able to look after any children (let alone young twins) on their own all day. Nor would they want to.
Having said that, I understand that nursery fees for twins would be prohibitive!
Aupair world dot net might be a good place to have a look, so you can get an idea of the sorts of people looking to come over the the UK as an aupair. I saw lots of adverts from slightly older (25-35yo) women, with some nannying, aupair or nursery experience who might be willing to take on a 'more than aupair but slightly less than nanny' job, with good hols, for less than 2 sets of nursery fees but more than aupair wages.
Good luck :)