The borrowing required for the pandemic is on a level comparable to WW1, WW2, the Napoleonic Wars and the Slavery Abolition Act 1833. I’m unsure about the Napoleonic Wars, but the debt for WW2 was finally paid off in 2006 and the Slavery Abolition Act in 2015. The final payments relating to debt incurred in WW1 was also paid off in 2015. The pandemic debt must be on these terms.
In the time between those awful events and eventual repayment, we have had railways, airports, hospitals, housing and motorways built, plus the creation of the NHS, the welfare state, and unfortunately several other wars too. I think that investment in our infrastructure won’t be harmed as much as you think it will and projects like TRU should be good to proceed, given the benefits it will bring.