Honestly looking from the outside and regretting some of my money choices
Id put the £5k into my pension as a lump sum
Then Id stop putting the £100 from savings into the family pot every month and put that in either my pension, the government will reward you for doing this so if you put in £100 extra into your pension each money you'll only see £70 out of your pay packet approx. Or put the money into a regular savings account where you can't draw it out. Lock away your savings in a bond paying 6.05% or something similar
Then sit down and budget with your dp/dh
you live together and he may declare he's hopeless with money - well he's not a child and needs to be either stepping up and budgeting or going without. Why should your finances suffer, future pension etc due to his mistakes every month?
Whittle back your expenses to the knuckle - what do you really need to pay for every month:
council tax
mortgage
utilities - water, gas & electric
tv licence, one streaming service & internet
mobile phones, how many do you pay for and are they all needed - can you go on sim only and save £££
house insurance contents and building
Car Mot, service and fuel - do you need to make so many journeys, would an electric bike be better for some trips and ditch one car etc
Then look at the overpayment calculators - there is a great calculator on Martin Lewis site https://www.moneysavingexpert.com/mortgages/mortgage-rate-calculator/