So dh and I were talking and we need a bigger property due to an unexpected third dc. We have a v small 3 bedroom flat but there’s 8 years in between dc 1&3 (dc2 is opposite gender and his box room is so tiny, getting a single bed in was a struggle). It wouldn’t be idea, for dc 1&3 to share long term as dc1 would be a teenager when dc3 is five. She will need her own space for stuff etc. I guess it could be done but our living areas were getting too small for 4, let alone 5. This property was only meant to be for a few years anyway (been here 3) but house prices shot up round here since then, it’s crazy. Even if ours went up at the same rate, we’d still be £200k+ behind actual houses and that’s for a three bed. We can’t currently afford that. Dh crunched the numbers and said that if we live on £850 a month for the next two years then we can save about £50k which would obviously be very helpful. This also means separately to that we could pay off our flat in two years. So our cash in bank to put towards a next property would be around £250k. We’re in Scotland which means that we’d need approx £40k for the offers over value (if you don’t know, basically up here if so etching is worth say £300k, you’d be
paying 10-20% over that out of pocket, you can’t mortgage that extra % as it’s over the value of the property).
So it’d be £250k we’d have but probably £200k for a deposit on a property after over value and solicitors fees etc. But it means that for anything post bills, we’d have £850 a month. This needs to include food, nappies, fuel (don’t use a lot of fuel to be fair). Any entertainment. We’d have already paid for kids clubs and streaming services as part of our bills, this is separate to the £850. We worked out that means we would have the money for one fun activity a month such as soft play/inflatable world etc. We do have lots of really good parks a short drive away although the weather is unpredictable at best 
. We currently spend about £350 each on the two older dc at Christmas but dh reckons we’d need to reign it in to closer to £200. Birthdays are about £200 each, so trying to get closer to £100 etc.
I guess I’m asking if it’s worth being frugal for two years with the dc at the ages that they are (9,7, baby) or if this will be too tight? We’ve also agreed that we will do a one week holiday abroad a year. I feel bad that Christmas and birthdays will be less as well as just day to day entertainment etc. Of course they won’t go without anything but it’ll be all clothes off Vinted kind of stuff (not slating it, both mine and baby’s wardrobes are 100% Vinted purchases). Would you do this or would it be too hard? Thank you for any replies.