The price of steel has actually been on a steady decline since the pandemic, not surprisingly as interest rates have stopped many from building and there’s not the same demand.
140 ish in 2017, 170 ish now.
Labour is more post Brexit, but not “far more”, up around 4% although interest rates and less construction demand are likely to reign those in somewhat also.
It’ll be more expensive than Spurs of course, but as posted above, London is the most expensive city in the World to build in, and 2 billion quid in an incredible sum of money.