In the days of Manor Houses and Lords were English surfs really just slaves?

Surfs up,  ah the classic sounds of the Beach Boys  lolz.

Serfs were bound to the land, but also they had their own property, and could buy their freedom.  

Serfs were contracted to work for the owner of the land, usually lord of the manor, but also had many days when they could work for themselves, they also often had their own share of 'Common land', or a piece of land around their dwelling, usually a hovel.  

In England one of the main reasons serfdom died out was due to there being a stable currency, and money in circulation, so a serf could save that money and buy their freedom.

Note England was not a money economy until around the late Tudor (16th century) period long after serfdom had effectively ended, but money being available instead of working in kind (food, lodging, clothing) ensured that a person could save what little they did earn, and buy their freedom.

The Black Death in England 1348,  saw the death knell of serfdom.  

Serf: an agricultural labourer bound by the feudal system who was tied to working on his lord's estate.The UK is still feudal in many ways to this very day.E.G.Their political voting system is feudal.

Surf: the mass or line of foam formed by waves breaking on a seashore or reef.

Stand or lie on a surfboard and ride on a wave towards the shore, Surf the internet.

They weren't basically slaves but the gentry did keep them down as they were easier to control.  The serfs were actually independent people but had to pay taxes (generally paid in grain and animals) and rents to the lord of the manor which did keep most of them living basically a subsistence lifestyle of hard work and little possible way out of this hard life.  Lack of possible education also kept them from improving their life and likely to small plots of land they were rented kept them from producing large profitable crops.

  Those with some abilities managed to start businesses like inns, flour mills, blacksmithing etc. and raised themselves out of the poverty of being a serf, but for many they were kept down by the gentry as that is the way the gentry liked it where they were powerful lording their power over the lower classes.  Likely many serfs were so scared they would have their land taken away they were very respectful and subservient to their lord, basically groveling to keep in his good books.

Virtually, until the plague created a demand for labor.

In some ways , bring a serf was worse than being a slave. Slaves cost their owners money so were at least fed. For all intents and purposes they were really agricultural machines. 

Serfs in the other hand had to work the land in return for some sort of rent , probably a percentage of the harvest. Poor harvest meant they starved, no one cared for them.

In practice they were free men, but in reality belonged to the manor as if they were slaves. 

So not much white privilege there?

The British have Not had slaves of any kind once the Romans left serfdom is Not Slavery serfs were paid

No indeed, they had much to do with the sea. But the serfs were.

Read or watch on YouTube "Terry Jones' Medieval Lives" (Or do both, as I did. You will chuckle at the video The book is more informative, and has the citations.)  Watch the episode "The Peasant" 

 Mr. Jones was a medieval scholar as well as a member of the "Monty Python" troupe. The aim of his book and t v. program was to debunk myths and misconceptions about the Medieval English.

No, they were not.

There wasn't any surf anywhere near an English manor house unless it was right on the coast.

Serfs were a step up from slavery. With a few exceptions, they could only be 'sold' along with the land they lived on. They were indentured servants, paying their debt for a place to live by working for the lord of the manor.

https://en.wikipedia.org/wiki/Serfdom