I see of the battle of the Somme is that the British command had sent men to their deaths and with no real gain

This is certainly an understandable position for people to take, when one considers the heavy casualties that the battle produced, notable the almost 60 000 casualties suffered on the First Day (July 1st, 1916), and the recurring spectacle in late July-August and October-November 1916 of disjointed, ill-supported attacks made against German positions often with no greater than battalion strength.

however the death tolls of the two sides are surprisingly similar.

They certainly were, just over 400 000 and 200 000 respectively for the British and French, and probably around 500 000 for the Germans.

Was the Battle of the Somme a success for the Brits or was it just a suicide mission?

THe key to understanding the Somme is that it was not simply a British campaign, but was in fact a joint-operation of the BEF and the French Army. Often forgotten in the discussions of July 1st and it's results is the fact that south of the Albert-Bapaume Road the attack by British XV and XIII Corps was almost entirely successful, while Gen. Fayolle's French 6th Army overwhelmed the German first position of trenches for along a c. 13 mile front. The Offensive did have the effect of significantly draining Germany's manpower reserves, requiring the raising of over 20 new infantry divisions to compensate, and conbined with the failure at Verdun and the results of the Brusilov Offensive, it led to the adoption of the Hindenburg Armaments Programme that ultimately exhausted Germany's coal and steel production, in addition to placing greater strain on civilian morale due to the adoption of conscription on the home front for vital war industries. It also had the immediate affect of forcing a German withdrawal to a new front line (the Siegfried Stellung) in 1917, which offered some tangible sign of success on the part of the Armies on the Western Front.

So at the strategic level, the Somme was a key moment in shifting the initiative towards the Allied (later Allied and Associated) Powers in 1916-17, although it was fumbled to a great degree as a result of the Nivelle Offensive in 1917. It wasn't a suicide mission or a defeat, but it did come at a high human cost, and the early hopes that it might produce a breakthrough were certainly unfounded.

Unless /u/jonewer has anything to add, I believe that should answer your question, unless you have further ones to ask?

u/DuxBelisarius who is sadly no longer active on reddit did an excellent write-up on the Somme in this thread