Blake's 7 was the story of a group of rebels fighting against the tyrannical Federation that rules over the Earth. A sort of space age Robin Hood. The show was created by Doctor Who writer and Dalek creator Terry Nation. It ran for four seasons on BBC 1 and was aimed very squarely at an adult audience. Some of the effects work was a little poor to the eye but at its heart the show was never about the flash and bang of space Oprah it was a tale of freedom fighters, cold criminal minds and political prisoners trying to overthrow an oppressive regime.
Unless I've missed something out, there isn't a space suit in sight until episode 10 of the second series in a story called Voices from the Past. This one saw Blake donning something a little spacey to go visit mining asteroid PK118, where he hopes to find some support in his efforts to raise a rebellion against the Federation.
Nothing too exotic here. I would like to get a closer look at the helmet but my guess is that it's been seen in some other show prior to this. The suit looks like it was run up for this episode by the shows costume designer.