Best way to cross

[braccoowner]

Hi, we’re just about to move to the Island, but DH will need to travel up to London a couple of times a week, so guessing he will need to take the Portsmouth route. Any thoughts about the best way to cross?

Hi - I imagine you have probably worked this out by now. However, in case you have yet to make the move - I would suggest that Southampton to London is quicker and the trains run more frequently.
My DP commutes from Cowes to the mainland every day using the Red Jet so has a season ticket which cuts down the cost hugely - but that would depend on how often your DH is going to be travelling.
Welcome to the Island.