I am Age 34, Civil Service, mortgage. £40k invested across ISA/LISA/SIPP.
Assuming 7% growth, and 450 invested into ISA pm. No investing after age 48.
My questions about my plan are:

• What part of this plan looks unrealistic
• Where do you see the biggest risks
• Would you retire at 48 on these numbers, latter or sooner
• I am open to various other options or ways of living

Expenses

Monthly expenses: £1,525/mo core expenses - lean FI
Future drops:

• Age 50: ‑£200 → £1,325/mo
• Age 57: mortgage ‑£270 → £1,055/mo

Bucket (48–50)

Covers first 2 years of retirement. Needs: £1,525 × 24 = £36,600

Bridge 1 — ISA (50–60)

ISA value is £207k 16 years of growth at 450 pm invested. Bridge 1 needs to cover 10 years: £1,325 × 12 × 10 = £150k

ISA £207k - £150k = £48k surplus

Bridge 2 — SIPP + LISA (60–70)

Current: £19.5k 26 years of growth is £113k. Bridge 2 needs to cover £1,055 × 12 × 10 = £126.6k

LISA/SIPP £113k - £126.6K = £13.6k short

Easy fix I have that 48k surplus

Bridge 3 — Alpha pension (70+)

Accrued: £4k year. Each year worked adds £750 x 14 = £10,500 +£4k = £14,500/year, there is costs of living adjustment each year, so flat numbers work.

Expenses £12,660 year, surplus £1,840