It is free money, however, I can only get at that money once I am at least 55 by which time I will hopefully be 20 years retired. I can't use the money and by the time I can, I won't need it.
TDLR; - don't be stupid - stay in the pension.
Giving up free money is not usually a good idea - and the pension system currently gives you quite a lot of free money.
Think about the rate of returns. If you pay off your mortgage, that's a return of a few % on your cash, depending on the interest rate you pay. If you put money in a pension you're getting way over 100% return - a contribution from you this year of £80 is adding £200 to your stash.
That money which you can't access until you're 55 (and almost certainly later than that in reality, they're bound to change the rules in the next 30 years) is still part of your stash. Between your RE date and your pension age, you're spending the part of the money that is outside the pension, but the money in your pension is continuing to grow, waiting to handle the 30+ years after the age of 55. The trick is to balance appropriately between the two so that you have enough money to handle the years before you get to the pension pot.
If you get to the point where you're paying 40% or 45% tax (or the horrible 60% zone between £100k and £122k), the pension contributions become a very efficient way to save because they are from pre-tax income. I'll pretty much hit my FIRE target number today, but I'm still contributing 75% of salary into my pension (using up previous year's allowances) because it's so efficient. OK, 55 is only a decade away for me, but the tax advantages make it by far the best investment.