If you anal douche 2/3 times a week, is it advisable to drink Actimel or something similar, as I've heard that douching can upset the natural bacteria in the gut and it needs replacing.

Anal douches don't reach the gut. They squirt a bit of water up probably no more than eight inches up.  The lower intestine is five feet long. Any microbes necessary in that last few inches will be replaced when the next poo comes passing through.

I had a colonic other week and was advised to take a prebiotic but douching wouldnt upset the balance