Help with DIY Lapland break please in Feb half term

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I already have (free) accommodation arranged in Levi, Lapland for February half term 2020 (16-23 Feb).
However I'm struggling to find affordable flights - I've had alerts set up, but now BA have sold out of direct flights on the way there, and looking at Finnair, Norwegian Air, Easyjet, the cheapest for our party of 4 is about £1700 (and not all direct, some without bags etc, there's so much variance and I'm getting over flu so my brain is actually hurting). These are also left in low numbers according to the booking sites.
I had thought about flying into Helsinki and getting the sleeper as I'd read it was €150 return for a family of four in a sleeper cabin but a) its €450 return which negates any savings and b) they don't have availability on our return date. I've chatted online with their Customer Service who can't confirm when their winter offer will start or what it will be.
Charter flights are coming back with direct with checked bags for £599pp.
Any advice or suggestions on booking - should I just grab what I can, go via Helsinki, look on any particular websites, contact a travel agent, wait for more to be released...?
Thanks in advance

Which UK airport are you flying from?

Thanks for the reply. I was flying from any London airport. BUT I've now found a decent option which although non-direct feels very manageable and gives us lots of time there. Sharing incase anyone is looking in future. We are taking the Eurostar to Brussels, easy transfer to At Pancras from our house, short check in time, 2 hour journey, and then a 21 minute transfer to the airport by train (included with Eurostar ticket). We're then staying one night in a family room at Accor hotel at the airport, and the next day we have an early flight by TUI direct from Brussels to Kittila, which gets us there 9am. We're returning the same way, although no hotel required, we'll use the left luggage at Brussels Midi and take an Uber into central Brussels for dinner before train home. The flights were €199 each on way there, €99 each on way back so even adding on the Eurostar and hotel it works out all in about £1500 with no hidden extras (eg if we had decided to fly we normally ends up paying for car parking at the airport), and we have the full day of arrival in Lapland too.
It was very close as we liked the idea of getting the night train but the clincher was only being able to afford flights which got us into Helsinki so early we would have had about 6 hours of hanging around for the train with all our cases, in the cold, and shattered from an early start.
Hope this helps someone else, and thanks again for the response!