If you don't like Mondays, why not Spa and Stay on Sunday, and then Spa again on Monday?
From just £139 per person your two day, one night package includes;
*Terms and Conditions apply. £40 single supplement. Valid on Sunday night bookings only. Rate based on two people sharing a standard room. Treatment to be taken on day of arrival. £139 per person when you book online, £152.90 per person when you book by telephone. Calls cost 4p per minute plus your phone company’s access charge.