Whatever you do, it's a total gamble. If S&P's were to downgrade UK debt (which would be quite logical, given that they've downgraded France, which is actually in a stronger position than the UK), then the pound could fall against the Euro. On the other hand, if Greece were to default (which seems increasing likely, given that talks with private lenders have collapsed) then the Euro would plunge against the pound.
As far as I can see, even the best financial minds in the world can't reliably predict what the situation will be in June.