Although a downgrade is a real PITA WT+ for a vacation trip to MCO is not too bad for a day flight. Especially if you let the crew know you were downgraded, you should hopefully get some extra special attention.
When you get back, go to the EU 261 thread here and pursue your full entitlement under EU 261 regulations, which is 75% of price paid (excl. legal taxs) for that sector. You will need to take a bit of a fight, especially as BA will try to decieve you regarding the 2-4-1, but it is straightforward and with a good argument from the experts here, you will almost certainly get the Avios back or cash equivalent awarded by MCOL.
Whatever you do, don't let it put a downer on your vacation!!