https://www.google.co.uk/flights/#se...A155;sc=b;eo=e
This isn't optimum for TP obviously but confirms that I is available both ways on those dates for example.
Seems like you almost have to be leaving CAI on a Sunday to make this work, but as I mentioned since a stopover is allowed that should make it possible to make this a 2-weekend deal with a stopover in DUB, MAD or wherever in the interim (and a nested return Dub-LHR to get you back to work for the intervening week.)