What to do with 30k

Hi all

This question gets asked a lot but in a sligghtttlyy different situation. Not the greatest sum of money but big enough that I have analysis paralysis.

We still have a mortgage to pay of 37k - was meant to be fully paid off by mid this year. Have just received a lumpsum and wondering what to do with the cash - could probably pay off the mortgage in full by the end of Feb if we put it towards the mortgage.

But I wasn't sure if that's the best way to use the money. We would have 350k sitting in a flexi account (so not paying interest on this but not gaining interest either) as well as 18k good energy home loan. Would there be any consequences to these if we fully pay off the other home loan?

I think my options are:

- chucking the money into a TD for around 4.8% - but after tax this may not be the smartest option?

- keeping the money in a bonus savings account but it'd only get like 3.35% I believe. We would keep it there until our next house or lump it all into ETFs if the market dips)

- chucking it all into VOO now (we have only just started investing in the last few months so it would be to catch up from the last few years of not investing).

Our home is valued around 1m and we intend on upgrading to a house around 1.5m ideally in around 1-3 years time. We would need to have a mortgage again but should only be around 300k if we can save up 200k or so in that time.

Any ideas, advice please? Open to hear any thoughts. Many thanks.