Plus, there are plenty of legitimate companies out there specialising in driving trips abroad.
You asked about track and number of nights stay earlier. Do you know what the going rate is for Circuit de Folembray in North France, 3 days 2 nights? It was including Eurotunnel too. £400 definitely seems too good to be true to me - Eurotunnel has got to be £150-200 ballpark right? So 3 days on track + accom. for £200?