Sabine here runs a session in Oban, I forget when.

The Ceilidh House in Ullapool often has events.

In between I'm not sure there is much that's scheduled regularly.

One place I went to recently for the first time is Kilmartin, south of Oban. It's one of the most interesting prehistoric sites in Britain. The B&B there is fine. Accessible by public transport (the bus from Oban to Lochgilphead). No live music that I know of though.

There are often events in Tobermory, sometimes other parts of Mull. The bus service on Mull is not very good, though- if you find something in Bunessan you won't be going anywhere when it finishes.

In much of the Highlands, tourist information offices know about folk events. Phone a few and talk to a human. You can usually afford to be flexible about where and when you go (maybe less so on Skye, it's the most heavily touristed per head of population).