You would combine 2 separate formulas and ADD up their results together:
1) For the 5,000 pounds, you use this formula:
FV =5,000 x [1 + 4%]^10
FV =5,000 x 1.04^10
FV =5,000 x 1.48024428491834392576
FV =7,401.22 Pounds
2) For the monthly payments of 75 pounds, you would use this formula. You still have to convert the interest rate from annual compound to monthly compound, which comes to 3.93% comp. monthly:
FV=P{[1 + R]^N - 1/ R}=FV OF $1 PER PERIOD.
FV =75 x {[1 + 3.93/1200]^(10x12) - 1} / 3.93/1200
FV =75 x {[1.003275]^120 - 1} / 0.003275
FV =75 x 146.70761
FV =11,003.07 Pounds
3) ADD 1 and 2 above together:
7,401.22 + 11,003.07 =18,404.29 - Pounds. The small differences of a few pennies is due to rounding off. Good luck to you.