What's your loan to value rate on the house? Also what are the rest of your financial circumstances, your age, employment status, do you work full/part time and are you looking to change this any time soon, what's your pension provision (and plans for retirement)? Are you a higher rate tax payer? Is the 170k all your savings or do you have more and if so where are they currently invested, have you used your full ISA allowance? Any DC and if so their ages and future plans, are you likely to need access to lump sums to support them with education/housing or other things in the near-ish future? Any debts inc car finance, credit cards, overdraft? Are you planning on staying in current house long term or will you need/want to move in next 5 -10 years? Does the house need any significant maintenance or value-adding work imminently and have you budgeted for this? Finally are you married, is the house owned jointly with anyone else and is the £170k something you would particularly want to protect in the event of a divorce/split (e.g. an inheritance)?
Sorry for all the questions and you absolutely don't have to answer them on a public forum but it's hard to give you a sensible answer without this info. Essentially by paying off your mortgage, yes you will save a significant amount in interest you would otherwise have paid on the mortgage (how much exactly will depend on your LTV and your access to the best mortgage deals if you choose to remortgage, there are a number of calculators online if you google) but equally by investing the same sum of money in other investment vehicles such as pension or stocks and shares you may well out-earn that (again depends on a number of factors e.g. whether you can put extra money into your pension which can be an extremely good, tax efficient thing to do, whether you can utilize ISA allowance). The other thing to consider is by putting all your money into your house and leaving yourself with very little other capital, your assets are very 'illiquid' ie you can't then easily use that money for anything else without either remortgaging or selling the house. This might not be a problem for you but as a bare minimum I would recommend keeping 3-6 months living expenses in case of emergency in a more accessible fund (an ISA if possible), plus if you have DC you know you want to put through uni, a new car you need to buy, major works to do on the house or other large expenses on the horizon also put that money aside, as if you end up having to use expensive forms of credit like overdraft, credit cards or car finance for those things whilst having loads of capital tied up in the house that would be silly and a waste of money. Also if you are married or in a relationship and the £170k is your inheritance you might want to consider whether putting it all into the marital/jointly owned home is really what you want to do, in the event of divorce or your premature death it could make it considerably harder to ensure that money comes back to you or is preserved for your children/family (sorry I know no-one wants to ever think about things but it's wise to be prepared).
Personally absent any other information I would potentially put a chunk of the £170 into reducing the mortgage, enough to enable me to access the best fixed term deal I could on the mortgage, then for the rest put aside funds for emergencies and known/planned expenditure as above, then invest the rest into my pension, ISAs and other risk-balanced investment vehicles. I'd then save the money I was saving on the mortgage to meet any long-term goals such as reducing hours at work, home improvements or retraining, grow my pension and investments and/or overpay the rest of the mortgage (one danger with paying off the mortgage is the temptation to 'fritter' away your new found 'disposable' income so beware of this and make firm plans for that money)...