There are dozens of different blood glucose meters on the market. Google will find them for you. A word of warning though - before you buy check the price of replacement test strips as you will need a lot of these, and you only need one meter. Many meters are given away for free, but the strips are very expensive, so do be careful. They all have to conform to the same accuracy standards before they can be marketed. They all require you to prick your finger for a blood droplet, which is then put on the strip so the meter can read the amount of glucose.
Many of this forum use the Codefree because it has the cheapest strips available. A new meter has hit the scene recently, called a TEE2 that also has cheap strips.
In addition to these meters, there is the Freestyle Libre sensor. This sits on your arm for 2 weeks with a tiny filament piercing the skin. It doesn't require blood. It measures the glucose in the interstitial fluid beneath the skin. You then scan the sensor for results. These are brilliant, but each sensor is above £50 and only lasts for 2 weeks.