The Londonderry Plantation was largely an English Plantation in the early 17th century - as mentioned many of the new settlements were built by the English and both the 'city' of Londonderry and the town of Coleraine were built primarily by English labour. A settlement was built as an executive headquaters for each of the 12 Company estate for example Ballykelly by the Fishmongers, and settlers lived in and around the villages as Derry was 'frontier territory' for the first four decades of the 17th century. Indeed maps of these settlements exist and most of the settlers in the villages were English and lived in English style houses. Some of these craftsmen actually ended doing quite well and became landholders. In the early period the settlers faced constant attack from the Irish Woodkerne. Sir Thomas Phillips, a servitor, and Englishman [although with Welsh roots] was granted the manor of Limavady and in 1612 he built Newtownlimavady a mile upstream from the old town and brought 25 English families to populate the new town, which became a Borough under his influence. Most of the office holders in the Borough had English sounding names so N'Limavady was a very English town. But the English never came in great numbers and indeed the native Irish were able to rent farms on the Phillips estate much to the chagrin of Phillips.
Scots started to come in larger numbers in the 1630s and soon were equal in number to the English. The 1641 rebellion shattered the new Plantation and many of the English went home never to return. In the aftermath of the rebellion during the Protectorate in the 1650s there was a massive influx of Scottish into north of the county in particular in the Baronies of Coleraine, Keenaught and Tirkeeran from Londonderry through Limavady and across to Coleraine when something like a second Plantation took place. Thus, if one compares the 1663 hearth money rolls with the 1630 muster rolls there is a distinct increase in Scottish surnames and a decrease in English sounding names. However, the English were still there and tended to be the landlords [for example Nicholas Lane in and around Ballykelly] and the Scots & Irish their tenants. Futher waves of Scots came in the 1660s and in the 1690's, and thus Presbyterian congregations were well established in many areas by the end of the century. The baptismal register for Ballykelly Presbyterian in the period 1699-1707 contains some 600 baptisms & the marriage register some 500 marriages in the years 1700-1728 showing that the Scottish colony was well established and embedded in the area [Ballykelly P Church served the Presbyterian inhabitants of Faughanvale, Tamlaght Finlagan and Magilligan].
It is very difficult to trace these early settlers back to Scotland or England - farmers and craftsmen leave little trace unlike the gentry and nobility. It may be possible if a settler had an unusual name. I have traced one family back to Scotland but they were minor landlords residing in the parish of Aghanloo, near Limavady - Abraham Hillhouse was listed with two hearths in the 1663 returns in Artikelly. He died in 1676 leaving a wife Janet and two known sons, Abraham Hillhouse jun his eldest son [received the 2 Largies & was at the siege of Derry] and his second son John Hillhouse received the manor house called Freehall and a fairly sizeable estate. Abraham Hillhouse senior also offset a tenement in the town of Irvine in Ayrshire upon his death so I assume that is where the family was from. But this is the exception rather than the norm in the course of research.
One could strike lucky for example in the Irvine parish registers of 1689 was the following baptism '7 July 1689: Elizabeth Fleeming, lau[ful]'ll daughter to James Fleeming & Jane Moor, parishe of Bellskellie [Ballykelly] & Co of Londonderrie in Irland, baptized'. This family appear to have gone home to their roots for refuge during the Williamite wars in Ireland, and the 'siege of Derry' ended three weeks after the child was baptised.
The key is to keep digging and to keep looking for the source material relating to the region where our ancestors resided. It is the sources that throw up the names. Keep a note of neighbours and kinsmen and think laterally because with the laws of diminishing returns it becomes fruitless if one just concentrates only on the family name. The good genealogist is also a good local historian.