How do I compare these two mortgages?

For the immediate question (do you save over 2 years) check the following:

If interest rates remain the same for the next 2 years, what will the total of the 24 payments be on both Mortgages? Then add the £1499 fee to the fixed rate payments. If the total on the tracker is lower than the total on the fix, then assuming nothing changes in base rate you're better on the tracker (and visa versa).

However, there are all sorts of variables you can't account for, for example - If base rate comes down then the tracker could win out regardless of the above, and if after the 2 years of your fix there's no equivalent tracker available then in the long term you could be worse off either way.

Basically your adviser is correct - It's impossible to compare directly. Nevertheless, they should be advising you, which means finding out about your personal circumstances and making a recommendation on it.

Important to note: Your adviser cannot predict the future, but they can figure out what kind of risks you're willing to take with future interest rate movements.

Why do brokers just avoid doing the obvious?

You can compare you just need to put in parameters and assumptions so you can analyse and make choices based on those.

The obvious first comparison is to assume variable rates won't change.
(which was the new norm till they went down)

have a tracker that is currently 1.74%

I have the option to move to a 2 yr fixed at 1.24%, with a £1499 fee.

My mortgage is £240,000 25 year term

@1.79% that's about £987pm

You have 2 options for 2 years paying £987

£240000 @ 1.74% £224,506
£241499 @ 1.24% £223,588

save about £900k after fees

For the variable rate to break even you can do some "what if' on a rate change.

today it would need to be 1.56% you can do the same for a change any time and also factor in rises

Are rates going down, your call but probably not enough.....

so the interesting part is what happens if rates go up and what happens after the 2 years.

what's the follow on after the fix(might make that tracker look good) and what are your guesses at the fees.

might you move and not b able to port...

is that variable lifetime?

Loads of variables longer term but some basic questions(like the one you asked) will this mortgage be cheaper over 2 years can be answered with some simple caveats.