An excellent site

https://www.investopedia.com/articles/economics/08/determining-oil-prices.asp

gives an in-depth analysis of what determines oil prices.

The current price of oil is constantly changing, and you can view the barrel price at https://oilprice.com/

Brent Crude is the relevant commodity applying to our market.

The oil trade is in US$ (United States Dollar), so the exchange rate for $US to £UK comes into effect.

This exchange rate is constantly changing, and you can view it at https://www.x-rates.com/graph/? 

When the £ is high, oil prices for us are lower.