Russia had already invaded Chechnya in 2000. This did not stop Tony Blair from pushing for oil deals:

https://www.theguardian.com/business/2003/feb/13/russia.poli...

Here is a site that claims that the deals went on well after the Crimea annexation:

https://www.declassifieduk.org/under-putin-mi6-linked-bp-ext...

I do not know the second site, so search and check for yourself. Britain also took gas via the Nordstream network that had a pipeline through Northern Germany to England.

I would direct such criticisms towards Blair and not towards someone who was under tremendous pressure and frankly fearing for his life.