Here a balanced article about the budget (which is significantly higher than the defence budgets of the earlier Tory governments).

What the Defence Investment Plan means for the Royal Navy

Large sums are necessary for the nuclear deterrent (SSBN) and the new SSN - and there is a shift to unmanned ships. The number of destroyers and frigates will be increased again, when the delayed Type 26 and Type 31 will be completed. The main driver of the decline of their numbers are that the too old Type 23 have to be decommissioned before their replacements are in service (something not related at all to the current budget).

New amphibious vessels will be built:
Four amphibious vessels to be built for the Royal Navy based on Dutch design