What does your DP say? Do they want to move in with you either now or in the future? 2 hrs away equates to a lot of mileage/distance. Yrs ago i moved a mere 1 hr away from all my friends and family, for a more village life for me and my DC but , it may well have been a whole universe away as friendships and relationships faded due to unwillingness to travel on their part. I got tired of always being the one to make all the effort and do all the travelling. This has led me to feel isolated where i am at times, in terms of people as , the village is quite cliquey and i have no support network or real friends here. I will be moving away in a few yrs but I am effectively single (just casually dating) and have that freedom to do that for myself , once youngest finished A levels. I need to consider no other and make it clear from the start to anyone i meet.
You need to spk to yr DP, they themselves may not want to ever leave where they are now and knowing what i know now, i would not blame them or you for staying put where you are. Also, even in 3 or 4 yrs time they may still want to be near their children, the youngest of whom , will still only be 18 at that time and maybe looking at tertiary/uni learning or even moving in with yr DP for a while, who knows .
How old are your DC? If young, has your DP ever said they would want to move in with you and a younger children dynamic even when theirs are grown? It is a big ask of someone.
With kindness, personally , i would not uproot my children and as a parent of 2 now almost grown DC, nor would i want to start again with a partners younger children. I also would not want to live somewhere that ordinarily i would not personally single out or chose to live ( if partner were not living there ) or share finances again.
I think you need to understand what your partner is thinking. Personally , i would not uproot myself or my children for another person for what is effectively a long distance, child free days only, relationship, albeit a 2 yr one. There is also both of your work and careers to think of. How would the others be affected if they relocated?
You need to spk to yr DP as this may not be what they want and as you have no so far ever lived together for any period of time i would not suggest you move anywhere. If their longer term idea /view of this relationship does not match yours, you may need to move on, if you are looking to a move in /long term retire together type partnership .