You really do need to get your BP checked today. Ring the labour ward and ask if you can come in for a check up. In the meantime, lie down with your feet up to try and get the swelling down. Fluid retention can be an indicator of pre-eclampsia.
I feel well enough - apart from heartburn, tiredness, pregnancy irritability etc! I'll put my feet up and if it hasn't gone down by tomorrow I'll ring the labour triage ward thingy.... does that sound reasonable?
Well it could be a DVT especially if your calf is hot/red as well as swollen. You really need to see these things. If it was me I wouldn't take the risk and would prefer a medic to look at it just to make sure.
Do check it out with a professional, but for what it's worth I've had one swollen ankle for weeks, a normal BP and no other problems so it can be 'normal' as well. You won't know if you don't get checked though so don't hesitate to do so!